Viruses

• Virus: a small infectious agent that can reproduce in a host cell.
• Viruses are strands of genetic material encased with a protein coat.
• Baltimore Classification System;

  1. Type of nucleic acid, DNA or RNA 

  2. single stranded or double stranded
  3. Use of reverse transcriptase
• Lytic Cycle:

  1. Attachment to cell wall or membrane
  2. Entry of genetic material into cell
  3. Replication of viral parts
  4. Assemble viral parts of virus
  5. Lyse, new viruses released
• Lysogenic Cycle: the viral DNA becomes part of the host cells chromosomes permanently. Now known as a provirus.
• Lysogenic Cycle;

  1. Insert viral DNA
  2. Reproduce cell with viral DNA
  3. Remove viral DNA, or go to Lytic cycle
• DNA Viruses: infects a host through chance encounter, have the same genetic material as humans.
• RNA Viruses: genetic material are made of RNA
• Retroviruses: work backwards, convert RNA to DNA before inserting into host cell.
• Bacteriophage: virus that infects bacteria, it injects it's DNA into bacteria to make viral parts.
• Virulence: the ability of a virus to cause disease.
• Virotherapy: uses viruses to treat bacterial diseases.
• Spread of Viruses:

  1. Vector: through an animal who carries the virus
  2. Airborne: coughing and sneezing
  3. Direct Contact: touching a surface previously touched by someone infected.
  4. Fecal Oral: contaminated hands, food or water.
  5. Sexually Transmitted: direct transfer of bodily fluids.